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Carbohydrates are chains of sugars found in grains, fruits, vegetables, beans and dairy products. In order to be absorbed and converted to energy in the body, carbohydrates must first be broken down in the digestive tract by proteins called enzymes. An enzyme known as amylase breaks down a carbohydrate called starch.

Starch

Starch is a type of carbohydrate made of a sugar called glucose. The glucose in starch is arranged into long chains by chemical links called alpha bonds. Foods that contain starch include bread, rice, potatoes, beans, peas and corn. When you eat these starchy foods, the alpha bonds are broken by an enzyme called alpha-amylase.

Alpha-Amylase in Saliva

Alpha-amylase is found in saliva. As soon as you eat starch, your saliva glands secrete this enzyme into your mouth. In fact, even the thought or smell of food can cause you to salivate. Alpha-amylase in saliva digests starch into pairs of glucose molecules, which are smaller, sweeter sugars. That's why starchy carbohydrates taste sweeter the longer they are in your mouth.

Alpha-Amylase from the Pancreas

Starches encounter alpha-amylase again when they reach the small intestine on their way through the digestive tract. The alpha-amylase is made by the pancreas and is secreted into the small intestine to finish digesting starches into pairs of glucose. These pairs are split into free glucose by another enzyme, and the glucose is absorbed by the small intestine to be used for energy.

Beta-Amylase

Although alpha-amylase is the only amylase used by humans, there is another version called beta-amylase, used by bacteria, molds and yeast. It breaks down starch so that those organisms can use it for energy. Beta-amylase is also found in plant seeds. It is what causes fruit to ripen and sweeten by breaking down fruit starches into smaller sugars.

About the Author

Dr. Elizabeth Gillman practices naturopathic medicine in Phoenix. She graduated from Southwest College of Naturopathic Medicine and also holds a degree in nutritional sciences from the University of Arizona. Gillman's writing is informed by her expertise in nutrition and wellness topics, especially healthy eating and lifestyle choices.